From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10DA3C5518C for ; Wed, 22 Apr 2020 08:14:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E51C52070B for ; Wed, 22 Apr 2020 08:14:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="mQsa+QXe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726451AbgDVIO0 (ORCPT ); Wed, 22 Apr 2020 04:14:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1725811AbgDVIOZ (ORCPT ); Wed, 22 Apr 2020 04:14:25 -0400 Received: from mail-wm1-x344.google.com (mail-wm1-x344.google.com [IPv6:2a00:1450:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E983CC03C1A6; Wed, 22 Apr 2020 01:14:24 -0700 (PDT) Received: by mail-wm1-x344.google.com with SMTP id v4so4280766wme.1; Wed, 22 Apr 2020 01:14:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:references:date:in-reply-to:message-id :user-agent:mime-version; bh=gcZwmzpZRozVbeeueq/lfLKF1YE2Wt6O6Z8WN9igdl4=; b=mQsa+QXeSYNo2dTVR3JqEP4N3d8jiSjSTcaw4vL+TujGAXv74FP5C/J44fhBnCd0Tt vY+mfGIHID7KJ59EQ/gQxCJsOz9hSShh2s3dHxK8YBOYxkB5hqMrTwaOcJ7ZZnJK42QM 32s929B8ZZtK10UeINRuaHSsOJT+QbsnOZrZxW1WZaY0A/KKL1D9Wks59qP7X2PR7fyL Fo0p3TE1dT8NP5bVAh12KRUf95y47XjPoAxjHumxfbvnGdEZ0aKg1SCVHeiL+atXU3o1 SR65CgmfMFiW7so27tKhEkHZeeDZIQal8T2h8RJ78NiFe8Ns4jbxHldQkLSr1aHmO5hf hQhA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:references:date:in-reply-to :message-id:user-agent:mime-version; bh=gcZwmzpZRozVbeeueq/lfLKF1YE2Wt6O6Z8WN9igdl4=; b=ms/ssngyyS1SV/TlnCmHO+5lEWx6D5dKC2lwbMGcI/3Ok6iMZZNth6vW1AgWu/Apxs zMtIB3TOsSxP7ZAnsbfvdJ3xS1JfYPMxEffF9rlRTMwMldv36VoHnWe1a3bA0bSdIzzA EuczIuZbK/K+OJjVqJDiKFYellCIZDLNZQqwkZ4pLxO5fFpW3fDUHEPTF2IlO7ecwvqH qKj/fxoh0/gKxFO5HVHH6CgEUFWFbwwKkGzwd4lR6N0I1yI+6mXJ4qfFBor8zkQYjzF8 i6qqJDmJr/4bCh/x/kiwRe0JQ+rZ2bCnvxhrUK3JfXNQIU0MG0Hfn+OFBCzSECXucu9Y yJyQ== X-Gm-Message-State: AGi0PuZ1FaujBGdJE3Xk5Us8ISqAhUgwof+nbrAbGD8RsR5Z4K6jfzy3 AJilj3/lLgK8wDJRHi/EY2+8g6QLel0= X-Google-Smtp-Source: APiQypIFeRvLPBvGOlE2vs2gyjN93pw7CkcVxnQtwefOITVt+0IY5bCY3jraVTYx9xUOe18V7AOGgw== X-Received: by 2002:a05:600c:1:: with SMTP id g1mr8919770wmc.142.1587543263394; Wed, 22 Apr 2020 01:14:23 -0700 (PDT) Received: from meru ([2a01:cb18:832e:5f00:1d35:d245:4470:8434]) by smtp.gmail.com with ESMTPSA id z8sm7319302wrr.40.2020.04.22.01.14.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Apr 2020 01:14:22 -0700 (PDT) From: Mathieu Othacehe To: Andy Shevchenko Cc: Jonathan Cameron , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald , linux-iio , Linux Kernel Mailing List Subject: Re: [PATCH v4 4/4] iio: vcnl4000: Add buffer support for VCNL4010/20. References: <20200421075532.19192-1-m.othacehe@gmail.com> <20200421075532.19192-5-m.othacehe@gmail.com> Date: Wed, 22 Apr 2020 10:14:21 +0200 In-Reply-To: (Andy Shevchenko's message of "Tue, 21 Apr 2020 15:27:14 +0300") Message-ID: <87tv1cos2q.fsf@gmail.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> +static int vcnl4010_buffer_predisable(struct iio_dev *indio_dev) >> +{ >> + struct vcnl4000_data *data = iio_priv(indio_dev); >> + int ret, ret_disable; >> + >> + ret = i2c_smbus_write_byte_data(data->client, VCNL4010_INT_CTRL, 0); >> + if (ret < 0) >> + goto end; >> + >> + ret = i2c_smbus_write_byte_data(data->client, VCNL4000_COMMAND, 0); >> + >> +end: > >> + ret_disable = iio_triggered_buffer_predisable(indio_dev); >> + if (ret == 0) >> + ret = ret_disable; > > What is this? > > Can't you rather call IIO API first, and then try to handle the rest? Well, iio_triggered_buffer_predisable will call free_irq which requires that the interruption source is disabled, hence this strange pattern. However, this may be some misunderstanding from me, but I noticed something strange here. In a configuration with one CPU and CONFIG_PREEMPT disabled, I have kernel lockups when disabling the buffer. This is because free_irq calls synchronize_irq that will wait for any IRQ handler to be over. If the kthread handling the interruption is still running, it has no chances to terminate, and synchronize_irq waits forever. So maybe I'm missing something. Anyway, I'll send a v5 addressing your remarks. Thanks, Mathieu